The present invention relates to an infrared rays heating unit of a microwave oven, more particularly to an infrared rays heating unit comprised of a heating coil.
The conventional inventions for a microwave oven with an infrared rays heating unit such as disclosed in Japanese Laid-Open Publications No. 55-20164(1980) and No. 53-140153(1978) are mainly concerned with a device which prevents high frequency rays generated from a magnetron from directly radiating the infrared rays heating unit.
As illustrated in FIG. 3, because the loops of the heating coil which is located in the infrared rays heating unit in the above conventional inventions, are generally arranged in a regular and dense pattern, the heating coil is inclined to become broken in a short time period due to the radiant heat generated during the operation of the infrared rays heating unit which becomes concentrated on the middle section of the infrared rays heating unit.
As a method for solving the above problem, several support members which hold the heating coil are installed at regular intervals in the infrared rays heating unit.
But, the disadvantages of such a configuration include the greater production costs and maintenance expenses.
It is an object of the present invention to provide a heating coil for an infrared rays heating unit comprised of a longer pitch interval in the middle section than at both end sections of the heating coil, thereby preventing the heating coil from easily becoming broken due to the concentration of radiant heat that is generated by the infrared rays heating unit and thereby considerably lengthening its service life.